Boolean Operators

Syntax

[ AND | OR | NOT ]

Parameters

SQL uses a three-valued Boolean logic where the null value represents "unknown."

a	b	a AND b	a OR b
TRUE	TRUE	TRUE	TRUE
TRUE	FALSE	FALSE	TRUE
TRUE	NULL	NULL	TRUE
FALSE	FALSE	FALSE	FALSE
FALSE	NULL	FALSE	NULL
NULL	NULL	NULL	NULL

a	NOT a
TRUE	FALSE
FALSE	TRUE
NULL	NULL

Notes

• The operators AND and OR are commutative, that is, you can switch the left and right operand without affecting the result. However, the order of evaluation of subexpressions is not defined. When it is essential to force evaluation order, use a CASE construct.
• Do not confuse Boolean operators with the Boolean-Predicate or the Boolean data type, which can have only two values: true and false.